Laquinimod is a compound which has been shown to be effective in the acute experimental autoimmune encephalomyelitis (aEAE) model (U.S. Pat. No. 6,077,851). Its chemical name is N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxoquinoline-3-carboxamide, and its Chemical Registry number is 248281-84-7. The processes of synthesis of laquinimod and the preparation of its sodium salt are disclosed in U.S. Pat. No. 6,077,851. An additional process of synthesis of laquinimod is disclosed in U.S. Pat. No. 6,875,869.
Pharmaceutical compositions comprising laquinimod sodium are disclosed in PCT International Application Publication No. WO 2005/074899.
Laquinimod sodium is a novel synthetic compound with high oral bioavailability, which has been suggested as an oral formulation for the treatment of Multiple Sclerosis (MS). (Polman, C. et al., (2005) “Treatment with laquinimod reduces development of active MRI lesions in relapsing MS”, Neurology. 64:987-991; Sandberg-Wollheim M, et al. (2005) “48-week open safety study with high-dose oral laquinimod in patients”, Mult Scler. 11:S154) Studies have also shown that laquinimod can reduce development of active MRI lesions in relapsing MS. (Polman, C. et al., (2005) “Treatment with laquinimod reduces development of active MRI lesions in relapsing MS”, Neurology. 64:987-991).
PCT International Application Publication No. WO 2010/028015 proposes deuterium-enriched variants of laquinimod. However, WO 2010/028015 cautions that, “[m]etabolic switching can lead to different proportions of known metabolites as well as altogether new metabolites” and such “new metabolic profile may impart more or less toxicity” which “are not predictable a priori for any drug class”. Thus, WO 2010/028015 does not provide at least the dosage for administration of the deuterium-enriched variants of laquinimod, and does not disclose the metabolic profile.